Optical characteristics measuring method and optical characteristics measuring system

ABSTRACT

An optical characteristics measuring method for measuring optical characteristics of a subject, the optical characteristics measuring method including: a step of acquiring one or more captured images including the subject, using an image capturing apparatus that is located at a predetermined distance from the subject, and is configured to be displaceable relative to the subject, while maintaining the predetermined distance; and a step of creating, based on the one or more captured images thus acquired, a virtual image including the subject and acquired from one or more analysis points each located at a position other than a position on a plane that includes the trajectory of the image capturing apparatus.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese patent application No. 2017-213964, filed on Nov. 6, 2017, thedisclosure of which are incorporated herein in its entirety byreference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an optical characteristics measuringmethod and an optical characteristics measuring system for measuringoptical characteristics of a subject.

Description of Related Art

Technology for measuring optical characteristics of a subject such as alight source has been developed. For example, JP 2016-151437A (PatentDocument 1) discloses an apparatus that measures illuminance at adistance from a light source.

Specifically, the light distribution characteristics measuring apparatusdisclosed in Patent Document 1 is a light distribution characteristicsmeasuring apparatus for measuring light distribution characteristics ofa light source, and includes: an image capturing unit that is located ata predetermined distance from the light source; a movable mechanism thatcontinuously changes the position of the image capturing unit relativeto the light source; and a processing unit that calculates lightdistribution characteristics of the light source based on a plurality ofpieces of image data captured by the image capturing unit, and relativepositions of the image capturing unit relative to the light source atpoints in time when the plurality of pieces of image data wererespectively captured. The processing unit acquires a plurality ofpieces of image data captured under first image capturing conditions anda plurality of pieces of image data captured under second imagecapturing conditions that are different from the first image capturingconditions. Also, based on first image information corresponding to arelative position of interest included in the plurality of pieces ofimage data captured under the first image capturing conditions, andsecond image information corresponding to the relative position ofinterest included in the plurality of pieces of image data capturedunder the second image capturing conditions, the processing unitdetermines corrected image information corresponding to the relativeposition of interest.

SUMMARY OF THE INVENTION

There is demand for technology that makes it possible to acquire morepreferable measurement results, with a configuration for measuringoptical characteristics of a subject, such as the light distributioncharacteristics measuring apparatus disclosed in Patent Document 1,using captured images of the subject.

The present invention has been made to solve the above-describedproblem, and an objective thereof is to provide an opticalcharacteristics measuring method and an optical characteristicsmeasuring system that can acquire more preferable measurement resultswith a configuration for measuring optical characteristics of a subjectusing captured images of the subject.

(1) An optical characteristics measuring method according to one aspectof the present invention is an optical characteristics measuring methodfor measuring optical characteristics of a subject, the opticalcharacteristics measuring method including: a step of acquiring one ormore captured images including the subject, using an image capturingapparatus that is located at a predetermined distance from the subject,and is configured to be displaceable relative to the subject, whilemaintaining the predetermined distance; and a step of creating, based onthe one or more captured images thus acquired, a virtual image includingthe subject and acquired from one or more analysis points each locatedat a position other than a position on a plane that includes thetrajectory of the image capturing apparatus.

The inventors of the present invention have conceived of measuring lightthat reaches the analysis points, from the viewpoint of what capturedimages can be acquired if images of the subject are captured from theanalysis points, instead of simply measuring the intensity of light fromthe subject, at the analysis points. As described above, with the methodof creating virtual images from the analysis points using an imagecaptured from a point located at a position other than the analysispoints, it is possible to reliably acquire a larger amount ofinformation at various analysis points, compared to a method of simplymeasuring the intensity of light from the subject at an analysis point.Therefore, it is possible to acquire more preferable measurementresults, with a configuration for measuring optical characteristics ofthe subject by using captured images of the subject.

(2) Preferably, in the step of creating a virtual image, a plurality ofvirtual images acquired from a plurality of analysis points arerespectively created, and the optical characteristics measuring methodfurther includes a step of calculating the sum of pixel values of eachof the plurality of virtual images thus created.

With such a method, it is possible to calculate the light intensity foreach analysis point. Therefore, it is possible to acquire thedistribution of intensities of light on any plane with high accuracy.

(3) Preferably, in the step of creating a virtual image, a capturedimage is selected from among a plurality of images captured from thetrajectory, based on a position on a virtual plane corresponding to thevirtual image, the position of each of the one or more analysis points,and the plane, and the virtual image is created based on the capturedimage thus selected.

With such a method, it is possible to select an appropriate capturedimage for each position on the virtual plane according to the positionon the virtual plane, the position of the analysis point, and thetrajectory. Therefore, it is possible to create a virtual image withhigh accuracy.

(4) More preferably, in the step of creating a virtual image, aplurality of captured images are selected from among a plurality ofimages captured from the trajectory, and the virtual image is createdbased on one image created from the plurality of captured images thusselected.

With such a method, in a case where there is no captured imagecorresponding to a position on the virtual plane and the position of theanalysis point, and captured from the trajectory, it is possible toselect a plurality of appropriate images and create a virtual image withhigh accuracy.

(5) Preferably, in the step of acquiring one or more captured images, aplurality of image capturing apparatuses that respectively captureimages with different wavelengths are used, and in the step of creatinga virtual image, the virtual image is created for each of the pluralityof image capturing apparatuses.

With such a method, it is possible to acquire, a plurality of capturedimages with a plurality of wavelengths captured at the same time, forexample. Also, it is possible to acquire captured images with differentwavelengths in parallel and shorten the image capturing period.Therefore, even if the intensity of light from the subject changes overtime, it is possible to acquire preferable captured images without beingsignificantly affected by such changes.

(6) More preferably, in the step of acquiring one or more capturedimages, a plurality of image capturing apparatuses that are arrangedalong the circumference of the same circle that is centered around thesubject are used.

By arranging a plurality of image capturing apparatuses such that thedistance between each image capturing apparatus and the subject is thesame, it is possible to simplify computation processing when, forexample, performing analysis using a plurality of virtual imagesrespectively created for the plurality of image capturing apparatuses.

(7) More preferably, in the step of acquiring one or more capturedimages, positional information indicating the position of each pixel ofthe one or more images captured by the plurality of image capturingapparatuses is corrected.

With such a method, even if the position of the subject is different ineach of the images captured by the plurality of image capturingapparatuses, it is possible to perform correction such that the positionof the subject in each captured image is the same, and then generate avirtual image for each wavelength. Therefore, it is possible to acquireeven more preferable measurement results.

(8) More preferably, in the step of acquiring one or more capturedimages, a plurality of image capturing apparatuses that respectivelyinclude light attenuation filters provided at positions in an imagecapturing direction are used.

With such a method, even if the light-transmission rates of theplurality of optical filters respectively provided in the plurality ofimage capturing apparatuses are different from each other, each imagecapturing apparatus can capture an image with an appropriate lightintensity.

(9) An optical characteristics measurement system according to oneaspect of the present invention is an optical characteristics measuringsystem that measures optical characteristics of a subject, the opticalcharacteristics measuring system including: an information processingapparatus; an image capturing apparatus that is located at apredetermined distance from the subject; and a movable mechanismconfigured to be able to change the position of the image capturingapparatus relative to the subject while maintaining the predetermineddistance. The information processing apparatus is configured to create avirtual image including the subject and acquired from one or moreanalysis points each located at a position other than a position on aplane that includes the trajectory of the image capturing apparatus,based on an image captured by the image capturing apparatus andincluding the subject.

The inventors of the present invention have conceived of measuring lightthat reaches the analysis points, from the viewpoint of what capturedimages can be acquired if images of the subject are captured from theanalysis points, instead of simply measuring the intensity of light fromthe subject, at the analysis points. As described above, with aconfiguration that uses an image captured from a point located at aposition other than the analysis points and is thereby able to create avirtual image acquired from the analysis point, it is possible toreliably acquire a larger amount of information at various analysispoints, compared to a configuration that simply measures the intensityof light from the subject at an analysis point. Therefore, it ispossible to acquire more preferable measurement results, with aconfiguration for measuring optical characteristics of the subject byusing captured images of the subject.

(10) Preferably, the information processing apparatus is configured tocreate a plurality of virtual images acquired from a plurality ofanalysis points respectively, and calculate the sum of pixel values ofeach of the plurality of virtual images thus created.

With such a configuration, it is possible to calculate the lightintensity for each analysis point. Therefore, it is possible to acquirethe distribution of intensities of light on any plane with highaccuracy.

(11) Preferably, the information processing apparatus is configured toselect a captured image from among a plurality of images captured fromthe trajectory, based on a position on a virtual plane corresponding tothe virtual image, the position of each of the one or more analysispoints, and the plane, and create the virtual image based on thecaptured image thus selected.

With such a configuration, it is possible to select an appropriatecaptured image for each position on the virtual plane according to theposition on the virtual plane, the position of the analysis point, andthe trajectory. Therefore, it is possible to create a virtual image withhigh accuracy.

According to the present invention, it is possible to acquire morepreferable measurement results, with a configuration for measuringoptical characteristics of the subject by using captured images of thesubject.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 shows an external configuration of an optical characteristicsmeasuring system according to an embodiment of the present invention.

FIG. 2 shows an apparatus configuration of the optical characteristicsmeasuring system according to the embodiment of the present invention.

FIG. 3 shows a configuration of a detector unit according to theembodiment of the present invention.

FIG. 4 illustrates changes in the positions of image capturingapparatuses according to the embodiment of the present invention.

FIG. 5 illustrates trajectories of the image capturing apparatusesaccording to the embodiment of the present invention.

FIG. 6 illustrates processing that is performed by an informationprocessing apparatus according to the embodiment of the presentinvention to calculate the light intensity.

FIG. 7A illustrates an example of a virtual image that is created by theinformation processing apparatus according to the embodiment of thepresent invention.

FIG. 7B illustrates an example of a virtual image that is created by theinformation processing apparatus according to the embodiment of thepresent invention.

FIG. 8 illustrates a method for creating a virtual image, employed bythe information processing apparatus according to the embodiment of thepresent invention.

FIG. 9 illustrates a method for creating a virtual image, employed bythe information processing apparatus according to the embodiment of thepresent invention.

FIG. 10 illustrates light analysis processing with respect to a point Pxshown in FIG. 9.

FIG. 11 illustrates compensation processing that is performed by theinformation processing apparatus according to the embodiment of thepresent invention.

FIG. 12 shows an example of the distribution of intensities of light,which can be acquired through analysis processing that is performed bythe information processing apparatus according to the embodiment of thepresent invention.

FIG. 13 shows an example of the distribution of intensities of light,which can be acquired through analysis processing that is performed bythe information processing apparatus according to the embodiment of thepresent invention.

FIG. 14 is a flowchart showing a flow of operations that are performedby the information processing apparatus according to the embodiment ofthe present invention.

FIG. 15 shows a configuration of a first modification of the detectorunit according to the embodiment of the present invention.

FIG. 16 shows a configuration of an optical filter unit included in thefirst modification of the detector unit.

FIG. 17 shows a configuration of a light attenuation filter unitincluded in the first modification of the detector unit.

DETAILED DESCRIPTION OF THE INVENTION

The following describes an embodiment of the present invention withreference to the drawings. Note that the same portions and equivalentportions in the drawings are assigned the same reference numerals andthe descriptions thereof are not repeated. At least some portions of theembodiment below may be combined in any manner.

Configuration and Basic Operations Optical Characteristics MeasuringSystem

FIG. 1 shows an external configuration of an optical characteristicsmeasuring system according to an embodiment of the present invention.FIG. 2 shows an apparatus configuration of the optical characteristicsmeasuring system according to the embodiment of the present invention.

As shown in FIGS. 1 and 2, an optical characteristics measuring system200 is a system that measures optical characteristics of a subject S,and includes an information processing apparatus 10, a detector unit 11,a movable mechanism 12, a spectrometer 13, and a supporting platform 14that supports the subject S.

The subject S is, for example, an object that emits light by itself,such as a light or a display device, or an object that reflects lightfrom a light source or allows it to pass therethrough. Specifically, thesubject S is, for example, a display such as a television, an indoorlight, an outdoor light, an automotive light, or a film. Note that theshape of the subject S is not limited to the spherical shape shown inFIG. 1.

The detector unit 11 includes one or more image capturing apparatuses31, specifically two-dimensional luminance meters. As shown in FIG. 2,the detector unit 11 includes three image capturing apparatuses 31A,31B, and 31C that respectively capture images with differentwavelengths. In the following description, each of the image capturingapparatuses 31A, 31B, and 31C may simply be referred to as an “imagecapturing apparatus 31”. The image capturing apparatuses 31 are locatedat a predetermined distance from the subject S.

The movable mechanism 12 changes the position of the detector unit 11relative to the subject S while maintaining the distance between thesubject S and the detector unit 11. As shown in FIG. 1, the movablemechanism 12 includes a first arm 21, a second arm 22, a first motor 23that can pivot in the direction indicated by an arrow E1, and a secondmotor 24 that can pivot in the direction indicated by an arrow E2.

As a result of the first motor 23 pivoting in the direction indicated bythe arrow E1, the first arm 21 coupled to the first motor 23, the secondarm 22 coupled to the first arm 21 via the second motor 24, and thedetector unit 11 attached to the second arm 22 pivot in the directionindicated by the arrow E1. Also, as a result of the second motor 24pivoting in the direction indicated by the arrow E2, the second arm 22coupled to the second motor 24 and the detector unit 11 pivot in thedirection indicated by the arrow E2.

Here, in FIG. 1, an axis that extends in a vertical direction is definedas a Y axis. Also, an axis that extends along a horizontal plane andextends in a direction from the subject S to the detector unit 11 whenthe detector unit 11 is located at the position shown in in FIG. 1 isdefined as a Z axis. Also, an axis that extends along a horizontal planeand is orthogonal to the Z axis is defined as an X axis.

The information processing apparatus 10 is connected to the imagecapturing apparatuses 31A, 31B, and 31C, the movable mechanism 12, andthe spectrometer 13. The information processing apparatus 10 transmits ameasurement command to the spectrometer 13 via a LAN (Local AreaNetwork) according to a user operation, for example. Upon receiving ameasurement command from the information processing apparatus 10, thespectrometer 13 measures the spectrum of light from the subject Saccording to the measurement command, and transmits the measurementresult to the information processing apparatus 10 via the LAN.

Also, the information processing apparatus 10 transmits a drive commandto the first motor 23 and the second motor 24 of the movable mechanism12 via the LAN according to a user operation, for example. Uponreceiving the driving command from the information processing apparatus10, the first motor 23 and the second motor 24 pivot according to thedrive command.

Also, the information processing apparatus 10 transmits an image capturecommand to the image capturing apparatuses 31A, 31B, and 31C via a GigE(Gigabit Ethernet (registered trademark)) according to a user operation,for example. Upon receiving the image capture command from theinformation processing apparatus 10, the image capturing apparatuses31A, 31B, and 31C respectively capture images that each include thesubject S at the center, in parallel, e.g. at the same time, accordingto the image capture command, and transmit the captured images to theinformation processing apparatus 10 via the GigE.

Also, the information processing apparatus 10 performs processing thatis described below, based on the measurement result from thespectrometer 13 and a plurality of captured images from the imagecapturing apparatuses 31A, 31B, and 31C, to analyze the opticalcharacteristics of the subject S. For example, the informationprocessing apparatus 10 calculates the light intensity at a given pointAp (hereinafter referred to as the “analysis point”) that is located ata position other than a position on a plane that includes thetrajectories of the image capturing apparatuses 31.

Specifically, the “position other than a position on a plane thatincludes the trajectories of the image capturing apparatuses 31” may beat least one of a position inside or outside the plane.

Detector Unit

FIG. 3 shows a configuration of the detector unit according to theembodiment of the present invention.

As shown in FIG. 3, the image capturing apparatuses 31A, 31B, and 31C inthe detector unit 11 are arranged along the circumference of the samecircle that is centered around the subject S, in the Y axis directionshown in FIG. 1. The image capturing apparatuses 31A, 31B, and 31Crespectively include cameras 41A, 41B, and 41C, optical filters 42A,42B, and 42C that are provided at positions in an image capturingdirection, and light attenuation filters 43A, 43B, and 43C that areprovided at positions in the image capturing direction. Note that theimage capturing direction is a direction from the image capturingapparatuses 31 to the subject S, for example.

The optical filters 42A, 42B, and 42C respectively allow light withdifferent wavelengths to pass therethrough. For example, the opticalfilter 42A allows light with a wavelength corresponding to the color redto pass therethrough, the optical filter 42B allows light with awavelength corresponding to the color green to pass therethrough, andthe optical filter 42C allows light with a wavelength corresponding tothe color blue to pass therethrough. Note that the optical filters 42A,42B, and 42C do not necessarily have characteristics that allow visiblelight to pass therethrough, and may have characteristics that allowinfrared or ultraviolet light to pass therethrough.

Due to such optical filters 42A, 42B, and 42C being provided, and alsodue to the image capturing apparatuses 31A, 31B, and 31C capturingimages of the subject S in parallel, the information processingapparatus 10 can acquire various kinds of images captured at the sametime, for example. In other words, it is possible to shorten an imagecapturing period during which images are captured. Therefore, even ifthe light-emission intensity of the subject S changes over time, it ispossible to acquire appropriate captured images without beingsignificantly affected by changes in the light-emission intensity.

The three light attenuation filters 43A, 43B, and 43C respectivelycorrespond to the optical filters 42A, 42B, and 42C, and adjust theamount of light such that light of an appropriate intensity reaches thecorresponding optical filters 42A, 42B, and 42C. As described above, dueto the configuration in which the light attenuation filters 43A, 43B,and 43C that are different from each other are respectively provided inthe image capturing apparatuses 31, even if the light-transmission ratesof the optical filters 42A, 42B, and 42C are different from each other,each image capturing apparatus 31 can capture an image with anappropriate light intensity.

FIG. 4 illustrates changes in the positions of the image capturingapparatuses according to the embodiment of the present invention.

FIGS. 1 and 4 are referenced here. As a result of the first motor 23shown in FIG. 1 pivoting as described above, the detector unit 11 pivotsabout the subject S, in the direction indicated by the arrow E1. Also,as a result of the second motor 24 pivoting, the detector unit 11 pivotsabout the subject S, in the direction indicated by the arrow E2. Inother words, as shown in FIG. 4, the image capturing apparatuses 31A,31B, and 31C in the detector unit 11 move along a spherical plane Spthat is centered around the subject S.

More specifically, the moving angle of each image capturing apparatus 31in the direction indicated by the arrow E1 is denoted as an angle φ, themoving angle of each image capturing apparatus 31 in the directionindicated by the arrow E2 is denoted as an angle θ, and it is envisionedthat the position of the image capturing apparatus 31B shown in FIG. 4is a position defined by “the angle φ=0°” and “the angle θ=0°”(hereinafter also referred to as the “initial position”). In this case,the image capturing apparatuses 31A, 31B, and 31C move along thespherical plane Sp, and accordingly the angle φ and the angle θ of eachimage capturing apparatus change.

Here, it is envisioned that the information processing apparatus 10transmits drive commands to the movable mechanism 12 so that the firstmotor 23 and the second motor 24 pivot in parallel. Consequently, it isunnecessary to stop the image capturing apparatuses 31 during the imagecapturing period in either the direction indicated by the arrow E1 orthe direction indicated by the arrow E2. Thus, it is possible to preventthe image capturing apparatuses 31 from wobbling as a result ofstopping. Also, since it is unnecessary to stop the image capturingapparatuses 31, the image capturing period can be short.

FIG. 5 illustrates trajectories of the image capturing apparatusesaccording to the embodiment of the present invention. In FIG. 5, thevertical axis indicates the moving angle θ of each image capturingapparatus 31, and the horizontal axis indicates the moving angle φ ofeach image capturing apparatus 31.

As shown in FIG. 5, when the image capturing apparatuses 31A, 31B, and31C move such that the angle φ changes within a range defined by0°≤φ<360° and the angle θ changes within a range defined by −90°≤θ<+90°,a trajectory La of the image capturing apparatus 31A, a trajectory Lb ofthe image capturing apparatus 31B, and a trajectory Lc of the imagecapturing apparatus 31C are as shown in FIG. 5. The image capturingapparatuses 31A, 31B, and 31C, which are provided at physicallydifferent angles relative to the subject S, move while maintaining thepositional relationship between one another in the detector unit 11.Therefore, the trajectories La, Lb, and Lc do not overlap each other.

Note that the trajectories La, Lb, and Lc are not limited to those shownin FIG. 5. Also, the image capturing apparatuses 31A, 31B, and 31C arenot necessarily configured to move along the spherical plane Sp shown inFIG. 4. That is, a plane that includes the trajectories of the imagecapturing apparatuses 31 may have a shape that is different from aspherical shape.

Also, the information processing apparatus 10 may transmit drivecommands to the movable mechanism 12 so that the first motor 23 and thesecond motor 24 are rotated one after the other.

Also, the image capturing apparatuses 31A, 31B, and 31C are notnecessarily arranged along the circumference of the same circle that iscentered around the subject S, in the Y axis direction shown in FIG. 1.

Also, the detector unit 11 may be configured without the lightattenuation filters 43A, 43B, and 43C.

Analysis Processing Performed by Information Processing ApparatusCalculation of Correction Coefficients

FIGS. 1 to 4 are referred to again. The information processing apparatus10 receives the measurement result of the spectrum of light, from thespectrometer 13, and calculates a correction coefficient for each of theimage capturing apparatuses 31, based on the measurement result thusreceived.

More specifically, the supporting platform 14 shown in FIG. 1 ispivotable in a direction indicated by an arrow E3. For example, the userrotates the supporting platform 14 to change the orientation of thesubject S such that the spectrometer 13 is positioned in front of thesubject S. In other words, the user changes the orientation of thesubject S such that the positional relationship between the spectrometer13 and the subject S is the same as the positional relationship betweenthe image capturing apparatus 31 at the above-described initial positionand the subject S. Thereafter, the information processing apparatus 10transmits a measurement command to the spectrometer 13 according to auser operation.

Upon receiving a measurement command from the information processingapparatus 10, the spectrometer 13 measures the spectrum of light fromthe subject S according to the measurement command, and transmits themeasurement result to the information processing apparatus 10. Theinformation processing apparatus 10 receives the measurement result fromthe spectrometer 13, and acquires, for example, tristimulus values Xλ,Yλ, and Zλ of light from the subject S, based on the measurement resultthus received.

Next, the user rotates the supporting platform 14 to change theorientation of the subject S such that the detector unit 11 ispositioned in front of the subject S. Thereafter, for example, theinformation processing apparatus 10 transmits drive commands to themovable mechanism 12 according to a user operation so that the imagecapturing apparatuses 31A, 31B, and 31C move to the initial position oneafter another, and thus the information processing apparatus 10 changesthe position of the detector unit 11.

Thereafter, the information processing apparatus 10 acquires an imagecaptured by the image capturing apparatus 31A at the initial position,an image captured by the image capturing apparatus 31B at the initialposition, and an image captured by the image capturing apparatus 31C atthe initial position.

The information processing apparatus 10 also acquires the intensity oflight of each color, based on the three captured images thus acquired.Specifically, the information processing apparatus 10 calculates theintensity of light with a wavelength corresponding to the color red,based on the image captured by the image capturing apparatus 31A fromthe initial position. The information processing apparatus 10 alsocalculates the intensity of light with a wavelength corresponding to thecolor green, based on the image captured by the image capturingapparatus 31B from the initial position. The information processingapparatus 10 also calculates the intensity of light with a wavelengthcorresponding to the color blue, based on the image captured by theimage capturing apparatus 31C from the initial position.

FIG. 6 illustrates processing that is performed by the informationprocessing apparatus according to the embodiment of the presentinvention to calculate the light intensity.

FIG. 6 is referenced here. When the intensities of light rays that reachan analysis point Ap from several points on the surface of the subject Sare respectively denoted as intensities I0, I1, I2, and so on, theintensity of light that reaches the analysis point Ap is the sum of theintensities I0, I1, I2, and so on.

Therefore, the information processing apparatus 10 acquires theintensity of light corresponding to the color red by totalling the pixelvalues of a plurality of pixels that are included in the image capturedby the image capturing apparatus 31A. The information processingapparatus 10 also acquires the intensity of light corresponding to thecolor green by totalling the pixel values of a plurality of pixels thatare included in the image captured by the image capturing apparatus 31B.The information processing apparatus 10 also acquires the intensity oflight corresponding to the color blue by totalling the pixel values of aplurality of pixels that are included in the image captured by the imagecapturing apparatus 31C.

Note that the information processing apparatus 10 may be configured toacquire the intensity of light of one color, based on a plurality ofimages respectively captured by the plurality of image capturingapparatuses 31. For example, the information processing apparatus 10 maybe configured to acquire the intensity of light corresponding to thecolor red, based on an image captured by the image capturing apparatus31A from the initial position and an image captured by the imagecapturing apparatus 31C from the initial position.

Thereafter, the information processing apparatus 10 calculatescorrection coefficients that are used to respectively equalize theintensities of light of the above-described colors acquired from thecaptured images with the tristimulus values Xλ, Yλ, and Zλ correspondingthereto acquired based on the measurement result from the spectrometer13.

Virtual Image Creation

Based on images captured by the image capturing apparatuses 31, theinformation processing apparatus 10 performs computation processing tocreate one or more images (hereinafter referred to as the “virtualimages”) of the subject S virtually captured from one or more analysispoints Ap each located at a position other than a position on thespherical plane Sp that includes the trajectories of the image capturingapparatuses 31.

FIGS. 7A and 7B each illustrate an example of a virtual image that iscreated by the information processing apparatus according to theembodiment of the present invention.

FIGS. 7A and 7B are referenced here. It is envisioned that a frontalimage of the subject S, i.e. an image of the subject S captured from theinitial position is the captured image shown in FIG. 7A. If this is thecase, the information processing apparatus 10 performs computationprocessing to create a virtual image of the subject S virtually capturedin an oblique direction relative to the subject S as shown in FIG. 7B,for example, i.e. virtually captured from an analysis point Ap locatedat a position that is different from the initial position.

FIG. 8 illustrates a method for creating a virtual image, employed bythe information processing apparatus according to the embodiment of thepresent invention. FIG. 9 illustrates a method for creating a virtualimage, employed by the information processing apparatus according to theembodiment of the present invention. In order to simply describe themethod for creating a virtual image, the following describes one imagecapturing apparatus 31.

As shown in FIG. 8, it is envisioned that the analysis point Ap islocated on the Y axis. If this is the case, the information processingapparatus 10 performs, as processing that is performed to create avirtual image captured from the analysis point Ap, an analysis on howthe subject S is projected onto a plane (hereinafter referred to as the“virtual plane) Vp at the center of which the subject S is located andthat is orthogonal to a vector extending from the analysis point Ap tothe center of the subject S, and thus acquires a virtual image.

Also, as shown in FIG. 9, in a case where the analysis point Ap is notlocated on the Y axis, the information processing apparatus 10 similarlyanalyzes how the subject S is projected onto the virtual plane Vpcorresponding to the analysis point Ap, and thus acquires a virtualimage.

More specifically, the information processing apparatus 10 performsprocessing to analyze light from the subject S with respect to severalpoints included in the virtual plane Vp. The following describes lightanalysis processing with respect to a point Px on the virtual plane Vpshown in FIG. 9.

FIG. 10 illustrates light analysis processing with respect to the pointPx shown in FIG. 9. FIG. 10 shows the respective positions of thesubject S, the spherical plane Sp centered around the subject S shown inFIG. 4, and the analysis point Ap.

FIG. 10 is referenced here. The information processing apparatus 10selects a captured image that is to be used to create a virtual image,from among a plurality of images captured by the image capturingapparatus 31, based on the position of the point Px on the virtual planeVp, the position of the analysis point Ap, and the spherical plane Sp.

More specifically, the information processing apparatus 10 specifies apoint D that is an intersection point of a straight line St and thespherical plane Sp, the straight line St passing through the point Px onthe virtual plane Vp and the analysis point Ap. Thereafter, theinformation processing apparatus 10 selects an image captured by theimage capturing apparatus 31 when the image capturing apparatus 31 waslocated at the point D, from among a plurality of captured imagesacquired by the image capturing apparatus 31.

Thereafter, the information processing apparatus 10 calculates pixelvalues of the virtual image, based on the pixel values, correspondingthereto, of the captured image thus selected, and thus creates thevirtual image.

More specifically, the information processing apparatus 10 specifies thepixel value of the pixel corresponding to the point Px on the virtualplane Vp, from among the pixels included in the captured image thusselected.

The information processing apparatus 10 specifies the pixel values ofall of the pixels included in the virtual image, and thus creates thevirtual image. Thereafter, the information processing apparatus 10performs output processing, which is processing performed to, forexample, display the created virtual image, which is the result ofanalysis, on a monitor or the like, or transmit the created virtualimage to another device.

Here, as shown in FIG. 5, the respective trajectories La, Lb, and Lc ofthe image capturing apparatuses 31A, 31B, and 31C do not overlap eachother, and therefore the image capturing apparatuses 31A, 31B, and 31Ccannot acquire an image captured from the same position. However, theinformation processing apparatus 10 performs computations using capturedimages to create a virtual image for each of the image capturingapparatuses 31A, 31B, and 31C, and thus the information processingapparatus 10 can create various kinds of images virtually captured fromthe same analysis point Ap.

Also, as described above, light rays with wavelengths corresponding tothe colors red, green, and blue respectively reach the cameras 41A, 41B,and 41C shown in FIG. 3. Therefore, the information processing apparatus10 can create a color virtual image by creating a virtual image acquiredfrom the same analysis point Ap for each image capturing apparatus 31,and by using the virtual images thus created.

Note that the method for creating a virtual image employed by theinformation processing apparatus 10 is not limited to theabove-described method, which is one example.

Compensation Processing

Here, there are cases where an image capturing apparatus 31 does notcapture an image when located at the point D that is an intersectionpoint of the straight line St and the spherical plane Sp shown in FIG.10, the straight line St passing through the point Px in the virtualplane Vp and the analysis point Ap. In such cases, the informationprocessing apparatus 10 can compensate for the image based on aplurality of images captured by the image capturing apparatuses 31.

FIG. 11 illustrates compensation processing that is performed by theinformation processing apparatus according to the embodiment of thepresent invention.

As shown in FIG. 11, the information processing apparatus 10 firstselects a plurality of points that are included in a trajectory L andare located in the vicinity of the point D. Thereafter, the informationprocessing apparatus 10 selects a plurality of images respectivelycaptured from the plurality of points thus selected, from among aplurality of images captured by the image capturing apparatus 31.Thereafter, using the plurality of captured images thus selected, theinformation processing apparatus 10 creates one image that could becaptured by the image capturing apparatus 31, assuming that the imagecapturing apparatus 31 was located at the point D.

For example, it is envisioned that the information processing apparatus10 selects four points P1, P2, P3, and P4. If this is the case, theinformation processing apparatus 10 creates the aforementioned oneimage, using four images respectively captured from the four points P1,P2, P3, and P4 thus selected.

Light Intensity Calculation Processing

The information processing apparatus 10 may be configured to output thelight intensity acquired based on the virtual image, as the result ofanalysis, instead of performing processing to output the created virtualimage as the result of analysis.

The information processing apparatus 10 calculates the light intensityby totalling the pixel values of the plurality of pixels included in thecaptured image, and multiplies the light intensity thus calculated, by acorrection coefficient. Thus, the information processing apparatus 10can calculate the light intensity at the analysis point Ap. For example,the information processing apparatus 10 multiplies the sum of the pixelvalues acquired from an image captured by the image capturing apparatus31A, by a correction coefficient corresponding to the color red. Thus,the information processing apparatus 10 can acquire a more accuratelight intensity.

Also, the information processing apparatus 10 creates a virtual imagefor each of a plurality of analysis points Ap, and calculates the lightintensity for each of the virtual images thus created. Thus, theinformation processing apparatus 10 can acquire the distribution ofintensities of light on a plane that is located at any position at adistance from the subject S.

FIG. 12 shows an example of the distribution of intensities of light,which can be acquired through analysis processing that is performed bythe information processing apparatus according to the embodiment of thepresent invention.

FIG. 12 is referenced here. The information processing apparatus 10calculates the light intensity for each of a plurality of analysispoints Ap included in a given plane, based on a plurality of imagescaptured by the image capturing apparatus 31A, for example. Thus, theinformation processing apparatus 10 can acquire an image Vd1 that showsthe distribution of intensities of light on the plane.

With such an image Vd1, it is easy to visually grasp, for example, thefact that the light intensity is high in an area R1 a that is locatednear the center of the plane, and the light intensity is low in aperipheral area R1 b.

FIG. 13 shows an example of the distribution of intensities of light,which can be acquired through analysis processing that is performed bythe information processing apparatus according to the embodiment of thepresent invention.

FIG. 13 is referenced here. The information processing apparatus 10calculates the light intensity with respect to each of a plurality ofanalysis points Ap included in a given plane, based on a plurality ofimages captured by the image capturing apparatus 31A, a plurality ofimages captured by the image capturing apparatus 31B, and a plurality ofimages captured by the image capturing apparatus 31C, and thus canacquire a color image Vd2 that shows the distribution of intensities oflight on the plane.

With such a color image Vd2, it is easy to visually grasp, for example,the fact that the intensity of light with a wavelength corresponding tothe color green is high in an area R2 a that is located near the centerof the plane, and the intensity of light with a wavelength correspondingto the color yellow is high in an area R2 b that is located slightlyabove the area R2 a, and the intensity of light with a wavelengthcorresponding to the color red is high in an area R2 c that is locatedslightly above the area R2 b.

Note that the analysis points AP are not limited to points located atpositions other than positions on the plane that includes thetrajectories of the image capturing apparatuses 31, and may be anypoints located on the spherical plane Sp. Specifically, the informationprocessing apparatus 10 may be configured to not determine whether ornot an analysis point Ap is located on the spherical plane Sp of theimage capturing apparatuses 31, and perform the same analysis processingregardless of whether the analysis point Ap is located on the sphericalplane Sp or is located at a position other than a position on thespherical plane Sp. With such a configuration, analysis processing canbe simplified.

Operational Flow

The information processing apparatus 10 includes a computer, and acomputation processing unit such as a CPU in the computer reads out,from a memory (not shown), a program that includes part or all of thefollowing steps of a flowchart, and executes the program. This programmay be externally installed. In addition, this program is distributed ina state of being stored on a recording medium.

FIG. 14 is a flowchart showing a flow of operations that are performedby the information processing apparatus according to the embodiment ofthe present invention.

As shown in FIG. 14, first, the information processing apparatus 10transmits a measurement command to the spectrometer 13. As a result, thespectrometer 13 measures spectrum. Thereafter, the informationprocessing apparatus 10 acquires the measurement result transmitted fromthe spectrometer 13, and holds the measurement result thus acquired(step S11).

Next, the information processing apparatus 10 changes the position ofthe detector unit 11 and acquires a plurality of images captured by theimage capturing apparatus 31A, a plurality of images captured by theimage capturing apparatus 31B, and a plurality of images captured by theimage capturing apparatus 31C, and hold the plurality of captured imagesthus acquired (step S12).

Next, for example, the information processing apparatus 10 acquires,from among the plurality of captured images thus acquired, an imagecaptured by the image capturing apparatus 31A from the initial position,an image captured by the image capturing apparatus 31B from the initialposition, and an image captured by the image capturing apparatus 31Cfrom the initial position (step S13).

Next, the information processing apparatus 10 calculates threecorrection coefficients respectively corresponding to the colors red,green, and blue, based on the captured images thus acquired and themeasurement result of the spectrum (step S14).

Note that the information processing apparatus 10 may acquire themeasurement result of the spectrum (step S11) at a point in time betweenthe acquisition of the captured images (step S12) and the acquisition ofthe images captured from the initial position (step S13), or between theacquisition of the images captured from the initial position (step S13)and the calculation of the correction coefficients (step S14).

Next, the information processing apparatus 10 sets an analysis point Apaccording to a user operation. For example, it is envisioned that theuser instructs the information processing apparatus 10 to output a colorimage showing the distribution of intensities of light on a given plane,as the result of analysis performed by the information processingapparatus 10. If this is the case, the information processing apparatus10 sets one of a plurality of points included in the plane indicated bythe user, as the analysis point Ap (step S15).

Next, the information processing apparatus 10 sets a point Px on thevirtual plane Vp corresponding to the analysis point Ap (step S16).

Next, for example, the information processing apparatus 10 specifies thepoint D, which is an intersection point of the straight line St and thespherical plane Sp centered around the subject S, the straight line Stpassing through the point Px and the analysis point Ap thus set (stepS17).

Next, the information processing apparatus 10 selects, for example, animage captured by the image capturing apparatus 31A when the imagecapturing apparatus 31A was located at the point D, from among theplurality of captured images held by the information processingapparatus 10. Note that, if the information processing apparatus 10 hasnot acquired an image captured by the image capturing apparatus 31A fromthe point D, the information processing apparatus 10 performs theabove-described image compensation processing to create an image thatcould be captured by the image capturing apparatus 31A, assuming thatthe image capturing apparatus 31A was located at the point D (step S18).

Next, the information processing apparatus 10 specifies the pixel valueof the pixel corresponding to the point Px on the virtual plane Vp, fromamong the pixels included in the captured image thus selected or created(step S19).

Next, the information processing apparatus 10 checks whether or not theinformation processing apparatus 10 has created a virtual image, i.e.whether or not the information processing apparatus 10 has specified thepixel values of all of the pixels included in the virtual image (stepS20). If there is a pixel whose pixel value has not been specified (“NO”in step S20), the information processing apparatus 10 sets a new pointPx corresponding to the pixel whose pixel value has not been specified(step S16), and performs step S17 and the subsequent processing.

On the other hand, if the information processing apparatus 10 hascreated a virtual image, i.e. if the information processing apparatus 10has specified the pixel values of all of the pixels included in thevirtual image (“YES” in step S20), the information processing apparatus10 determines whether or not the information processing apparatus 10 hascreated virtual images corresponding to the analysis point Ap for all ofthe image capturing apparatuses 31A, 31B, and 31C (step S21).

If the information processing apparatus 10 has not created a virtualimage for at least one of the image capturing apparatuses 31A, 31B, and31C (“NO” in step S21), the information processing apparatus 10 performsvirtual image creation processing, i.e. the processing in steps S16 toS20, with respect to the image capturing apparatus 31 for which avirtual image has not been created.

On the other hand, if the information processing apparatus 10 hascreated virtual images for all of the image capturing apparatuses 31A,31B, and 31C (“YES” in step S21), the information processing apparatus10 calculates, for each of the created virtual images, the sum of thepixel value of the plurality of pixels in the virtual image, andcalculates a value by multiplying the sum by the correction coefficient,as the intensity of light. Thereafter, for example, using the pluralityof intensities respectively calculated for the plurality of virtualimages, the information processing apparatus 10 calculates the lightintensity at the analysis point Ap for each wavelength (step S22).

Next, the information processing apparatus 10 checks whether or not theinformation processing apparatus 10 has calculated the light intensityfor all of the points included in the plane specified by the user (stepS23). If there is a point for which the light intensity has not beencalculated (“NO” in step S23), the information processing apparatus 10sets a new analysis point AP (step S15), and performs step S16 and thesubsequent processing.

On the other hand, if the information processing apparatus 10 hascalculated the light intensity for all of the points included in theplane specified by the user (“YES” in step S23), the informationprocessing apparatus 10 creates, for example, a color image showing thedistribution of intensities of light, based on the light intensitycalculated for each point. Thereafter, the information processingapparatus 10 performs processing to output the image thus created, asthe result of analysis (step S24).

Note that the user may specify, on the information processing apparatus10, any type of data as data that is to be output from the informationprocessing apparatus 10 as the result of analysis, according to the typeof subject S, for example.

For example, it is envisioned that the user instructs the informationprocessing apparatus 10 to output a color virtual image acquired fromthe analysis point Ap. If this is the case, the information processingapparatus 10 does not perform the processing in step S22 or S23, createsa color virtual image using three virtual images respectivelycorresponding to the image capturing apparatuses 31A, 31B, and 31C, andoutputs the color virtual image thus created, as the result of analysis.

Also, it is envisioned that the user instructs the informationprocessing apparatus 10 to output a virtual image acquired from theanalysis point Ap and corresponding to the image capturing apparatus31A, for example. If this is the case, the information processingapparatus 10 does not perform the processing in steps S21 to S23, andoutputs a virtual image corresponding to the image capturing apparatus31A as the result of analysis.

Also, it is envisioned that the user instructs the informationprocessing apparatus 10 to output an image showing the distribution ofintensities of light with a wavelength corresponding to the color red,on a given plane. If this is the case, the information processingapparatus 10 does not perform the processing in step S21 or S23, andcreates an image showing the distribution of intensities of light, basedon the light intensity at each of the plurality of analysis points Ap,which can be acquired from the virtual image corresponding to the imagecapturing apparatus 31A. Thereafter, the information processingapparatus 10 outputs the image thus created, as the result of analysis.

Note that the spectrometer 13 may be located inside the spherical planeSp in order to improve sensitivity, for example. That is, the distancebetween the spectrometer 13 and the subject S may be different from thedistance between the image capturing apparatuses 31 and the subject S.

If this is the case, when acquiring images captured from the initialposition (step S13), the information processing apparatus 10 creates avirtual image acquired from the analysis point Ap, assuming that thespectrometer 13 is located at the analysis point Ap, based on theplurality of captured images thus acquired.

That is, the information processing apparatus 10 sets the position ofthe spectrometer 13 as the analysis point Ap, and sets the point Px onthe virtual plane Vp corresponding to the analysis point Ap. Thereafter,the information processing apparatus 10 selects, from among the imagescaptured by the image capturing apparatuses 31, an image captured fromthe point D, which is an intersection point of the straight line St andthe spherical plane Sp, the straight line St passing through the pointPx and the analysis point Ap.

Thereafter, the information processing apparatus 10 specifies the pixelvalue of the pixel corresponding to the point Px on the virtual planeVp, from among the pixels included in the captured image thus selected.The information processing apparatus 10 specifies the pixel values ofall of the pixels included in the virtual image, and thus theinformation processing apparatus 10 can create the virtual imagecorresponding to the analysis point Ap as an image captured from theinitial position.

The information processing apparatus 10 is not necessarily configured tocalculate a correction coefficient, and may be configured to notcalculate a correction coefficient when the characteristics of thesubject S are known, such as when the relative intensity of light ateach wavelength is known. That is, the information processing apparatus10 may not perform the acquisition of the result of spectrum measurement(step S11), the acquisition of the image captured from the initialposition (step S13), or the calculation of the correction coefficient(step S14). Also, if this is the case, the optical characteristicsmeasuring system 200 shown in FIG. 1 may not include the spectrometer13.

There is demand for technology that makes it possible to acquire morepreferable measurement results, with a configuration for measuringoptical characteristics of a subject, such as the light distributioncharacteristics measuring apparatus disclosed in Patent Document 1,using captured images of the subject.

Considering this demand, with the optical characteristics measuringmethod according to the embodiment of the present invention, theinformation processing apparatus 10 first acquires one or more capturedimages including the subject S, using an image capturing apparatus 31that is located at a predetermined distance from the subject S, and isconfigured to be displaceable relative to the subject S, whilemaintaining the predetermined distance. Next, based on the one or morecaptured images thus acquired, the information processing apparatus 10creates one or more virtual images including the subject S and acquiredfrom one or more analysis points Ap each located at a position otherthan a position on the spherical plane Sp that includes the trajectoryof the image capturing apparatus 31.

The inventors of the present invention have conceived of measuring lightthat reaches the analysis points Ap, from the viewpoint of what capturedimages can be acquired if images of the subject S are captured from theanalysis points Ap, instead of simply measuring the intensity of lightfrom the subject S, at the analysis points Ap. As described above, withthe method of creating a virtual image from the analysis points AP usingan image captured from a point located at a position other than theanalysis points Ap, it is possible to reliably acquire a larger amountof information at various analysis points Ap, compared to a method ofsimply measuring the intensity of light from the subject S at ananalysis point Ap. Therefore, it is possible to acquire more preferablemeasurement results, with a configuration for measuring opticalcharacteristics of the subject S by using one or more captured images ofthe subject S.

Also, with the above-described method, it is unnecessary to position theimage capturing apparatus 31 at an actual analysis point Ap. Therefore,even if the analysis point Ap is remote from the subject S, it ispossible to reduce the distance from the subject S to the imagecapturing apparatus, and it is possible to downsize the overall system.

Also, with the optical characteristics measuring method according to theembodiment of the present invention, when creating a virtual image, theinformation processing apparatus 10 creates a plurality of virtualimages acquired from a plurality of analysis points Ap, respectively.Furthermore, the information processing apparatus 10 calculates the sumof pixel values of each of the plurality of virtual images thus created.

With such a method, it is possible to calculate the light intensity foreach analysis point Ap. Therefore, it is possible to acquire thedistribution of intensities of light on any plane with high accuracy.

Also, with the optical characteristics measuring method according to theembodiment of the present invention, when creating a virtual image, theinformation processing apparatus 10 selects a captured image from amonga plurality of images captured from the trajectory L, based on aposition on the virtual plane Vp corresponding to the virtual image, theposition of the analysis point Ap, and the spherical plane Sp, andcreates the virtual image based on the captured image thus selected.

With such a method, it is possible to select an appropriate capturedimage for each position on the virtual plane Vp according to theposition on the virtual plane Vp, the position of the analysis point Ap,and the trajectory L. Therefore, it is possible to create a virtualimage with high accuracy.

Also, with the optical characteristics measuring method according to theembodiment of the present invention, when creating a virtual image, theinformation processing apparatus 10 selects a plurality of capturedimages from among a plurality of images captured from the trajectory L,and creates a virtual image based on one image created from theplurality of captured images thus selected.

With such a method, in a case where there is no captured imagecorresponding to a position on the virtual plane Vp and the position ofthe analysis point Ap, and captured from the trajectory L, it ispossible to select a plurality of appropriate images and create avirtual image with high accuracy.

Also, with the optical characteristics measuring method according to theembodiment of the present invention, when acquiring one or more capturedimages, the information processing apparatus 10 uses a plurality ofimage capturing apparatuses 31 that respectively capture images withdifferent wavelengths, and when creating a virtual image, theinformation processing apparatus 10 creates a virtual image for each ofthe image capturing apparatuses 31.

With such a method, it is possible to acquire a plurality of capturedimages with a plurality of wavelengths, captured at the same time, forexample. Also, it is possible to acquire captured images with differentwavelengths in parallel and shorten the image capturing period.Therefore, even if the intensity of light from the subject S changesover time, it is possible to acquire preferable captured images withoutbeing significantly affected by such changes.

Also, with the optical characteristics measuring method according to theembodiment of the present invention, when acquiring one or more capturedimages, the information processing apparatus 10 uses a plurality ofimage capturing apparatuses 31 that are arranged along the circumferenceof the same circle that is centered around the subject S.

In this way, by arranging a plurality of image capturing apparatuses 31such that the distance between each image capturing apparatus 31 and thesubject S is the same, it is possible to simplify computation processingwhen, for example, performing analysis using a plurality of virtualimages respectively created for the plurality of image capturingapparatuses 31.

Also, with the optical characteristics measuring method according to theembodiment of the present invention, when acquiring one or more capturedimages, the information processing apparatus 10 uses a plurality ofimage capturing apparatuses 31 that include light attenuation filters43A, 43B, and 43C that are provided at positions in the image capturingdirection.

With such a method, even if the light-transmission rates of theplurality of optical filters 42A, 42B, and 42C respectively provided inthe plurality of image capturing apparatuses 31 are different from eachother, each image capturing apparatus 31 can capture an image with anappropriate light intensity.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, an image capturing apparatus 31is located at a predetermined distance from the subject S. The movablemechanism 12 is configured to be able to change the position of theimage capturing apparatus 31 relative to the subject S while maintainingthe predetermined distance. Based on an image captured by the imagecapturing apparatus 31 and including the subject S, the informationprocessing apparatus 10 can create a virtual image including the subjectS and acquired from one or more analysis points Ap each located at aposition other than a position on the spherical plane Sp that includesthe trajectories L of the image capturing apparatuses 31.

The inventors of the present invention have conceived of measuring lightthat reaches the analysis points Ap, from the viewpoint of what capturedimages can be acquired if images of the subject S are captured from theanalysis points Ap, instead of simply measuring the intensity of lightfrom the subject S, at the analysis points Ap. As described above, witha configuration that uses an image captured from a point located at aposition other than the analysis points Ap and is thereby able to createa virtual image acquired from the analysis point, it is possible toreliably acquire a larger amount of information at various analysispoints Ap, compared to a configuration that simply measures theintensity of light from the subject S at an analysis point Ap.Therefore, it is possible to acquire more preferable measurementresults, with a configuration for measuring optical characteristics ofthe subject S by using captured images of the subject S.

Also, with the above-described configuration, it is unnecessary toposition the image capturing apparatus 31 at an actual analysis pointAp. Therefore, even if the analysis point Ap is remote from the subjectS, it is possible to reduce the distance from the subject S to the imagecapturing apparatus, and it is possible to downsize the overall system.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, the information processingapparatus 10 creates a plurality of virtual images acquired from aplurality of analysis points Ap respectively, and calculates the sum ofpixel values of each of the plurality of virtual images thus created.

With such a configuration, it is possible to calculate the lightintensity for each analysis point Ap. Therefore, it is possible toacquire the distribution of intensities of light on any plane with highaccuracy.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, the information processingapparatus 10 selects a captured image from among a plurality of imagescaptured from the trajectory L, based on a position on the virtual planeVp corresponding to the virtual image, the position of the analysispoint Ap, and the spherical plane Sp, and creates the virtual imagebased on the captured image thus selected.

With such a configuration, it is possible to select an appropriatecaptured image for each position on the virtual plane Vp according tothe position on the virtual plane Vp, the position of the analysis pointAp, and the trajectory L. Therefore, it is possible to create a virtualimage with high accuracy.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, the information processingapparatus 10 selects a plurality of captured images from among aplurality of images captured from the trajectory L of the imagecapturing apparatus 31, and creates a virtual image based on one imagecreated from the plurality of captured images thus selected.

With such a configuration, in a case where there is no captured imagecorresponding to a position on the virtual plane Vp and the position ofthe analysis point Ap, and captured from the trajectory L, it ispossible to select a plurality of appropriate images and create avirtual image with high accuracy.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, a plurality of image capturingapparatuses 31 respectively capture images with different wavelengths.Also, the information processing apparatus 10 creates a virtual imagefor each of the image capturing apparatuses 31.

With such a configuration, it is possible to acquire a plurality ofcaptured images with a plurality of wavelengths, captured at the sametime, for example. Also, it is possible to acquire captured images withdifferent wavelengths in parallel and shorten the image capturingperiod. Therefore, even if the intensity of light from the subject Schanges over time, it is possible to acquire preferable captured imageswithout being significantly affected by such changes.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, the image capturing apparatuses31 are arranged along the circumference of the same circle that iscentered around the subject S.

In this way, with a configuration in which a plurality of imagecapturing apparatuses 31 are arranged such that the distance betweeneach image capturing apparatus 31 and the subject S is the same, it ispossible to simplify computation processing when, for example,performing analysis using a plurality of virtual images respectivelycreated for the plurality of image capturing apparatuses 31.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, the image capturing apparatuses31A, 31B, and 31C respectively include light attenuation filters 43A,43B, and 43C that are provided at positions in the image capturingdirection.

With such a configuration, even if the light-transmission rates of theplurality of optical filters 42A, 42B, and 42C respectively provided inthe plurality of image capturing apparatuses 31 are different from eachother, each image capturing apparatus 31 can capture an image with anappropriate light intensity.

First Modification

FIG. 15 shows a configuration of a first modification of the detectorunit according to the embodiment of the present invention.

In the above-described example, the detector unit 11 includes threeimage capturing apparatuses 31A, 31B, and 31C. In contrast, as shown inFIG. 15, the first modification of the detector unit 11 includes oneimage capturing apparatus 51. The image capturing apparatus 51 includesa camera 71, an optical filter unit 72 that is provided at a position inthe image capturing direction, and a light attenuation filter unit 73that is provided at a position in the image capturing direction.

FIG. 16 shows a configuration of the optical filter unit included in thefirst modification of the detector unit.

As shown in FIG. 16, the optical filter unit 72 includes, for example,three optical filters 62A, 62B, and 62C, and an opening 62D. The opticalfilters 62A, 62B, and 62C respectively allow light with differentwavelengths to pass therethrough. For example, the optical filter 62Aallows light with a wavelength corresponding to the color red to passtherethrough, the optical filter 62B allows light with a wavelengthcorresponding to the color green to pass therethrough, and the opticalfilter 62C allows light with a wavelength corresponding to the colorblue to pass therethrough. Note that the optical filters 62A, 62B, and62C do not necessarily have characteristics that allow visible light topass therethrough, and may have characteristics that allow infrared orultraviolet light to pass therethrough.

FIG. 17 shows a configuration of a light attenuation filter unitincluded in the first modification of the detector unit.

As shown in FIG. 17, the light attenuation filter unit 73 includes, forexample, three light attenuation filters 63A, 63B, and 63C, and anopening 63D. The three light attenuation filters 63A, 63B, and 63C arerespectively provided in correspondence with the optical filters 62A,62B, and 62C, and adjust the amount of light such that light of anappropriate intensity reaches the optical filters 62A, 62B, and 62Ccorresponding thereto.

The optical filter unit 72 and the light attenuation filter unit 73 areconnected to a motor (not shown), for example. The informationprocessing apparatus 10 shown in FIG. 1 transmits a drive command to themotor via a LAN according to a user operation, for example. Uponreceiving the drive command from the information processing apparatus10, the motor pivots according to the drive command. As a result of themotor pivoting, the optical filter unit 72 and the light attenuationfilter unit 73 integrally pivot in a direction indicated by an arrow E4.

As a result of the optical filter unit 72 pivoting, one of the opticalfilters 62A, 62B, and 62C and the opening 62D is positioned in front ofa lens 74 of a camera 71.

Also, the light attenuation filter unit 73 pivots such that the lightattenuation filter 63A is positioned in front of the lens 74 when theoptical filter 62A is positioned in front of the lens 74.

Also, the light attenuation filter unit 73 pivots such that the lightattenuation filter 63B is positioned in front of the lens 74 when theoptical filter 62B is positioned in front of the lens 74. Also, thelight attenuation filter unit 73 pivots such that the light attenuationfilter 63C is positioned in front of the lens 74 when the optical filter62C is positioned in front of the lens 74.

For example, in a state where the optical filter 62A is positioned infront of the lens 74, the information processing apparatus 10 transmitsan image capture command to the image capturing apparatus 51 whilerotating the first motor 23 and the second motor 24 shown in FIG. 1. Asa result, the information processing apparatus 10 acquires a pluralityof captured images including the subject S at the center andcorresponding to the color red.

Also, for example, in a state where the optical filter 62B is positionedin front of the lens 74, the information processing apparatus 10transmits an image capture command to the image capturing apparatus 51while rotating the first motor 23 and the second motor 24. As a result,the information processing apparatus 10 acquires a plurality of capturedimages including the subject S at the center and corresponding to thecolor green.

Also, for example, in a state where the optical filter 62C is positionedin front of the lens 74, the information processing apparatus 10transmits an image capture command to the image capturing apparatus 51while rotating the first motor 23 and the second motor 24. As a result,the information processing apparatus 10 acquires a plurality of capturedimages including the subject S at the center and corresponding to thecolor blue.

With such a configuration in which the optical filter unit 72 and thelight attenuation filter unit 73 are provided, it is possible to acquirevarious kinds of captured images without providing a plurality of imagecapturing apparatuses 51, and therefore it is possible to reduce costs.

Other configurations and operations are the same as those of theabove-described optical characteristics measuring system 200, detaileddescriptions are not repeated here.

Second Modification

The example above illustrates a case where images captured by the imagecapturing apparatuses 31 include the subject S at the centers of thecaptured images. However, the position of the subject S in a capturedimage may be displaced from the center of the captured image.Considering such a case, a second modification of the informationprocessing apparatus 10 can correct positional information indicatingthe position of each pixel of a captured image.

For example, the information processing apparatus 10 acquires, inadvance, for each image capturing apparatuses 31, a correction value forcorrecting positional information. Specifically, a correction valueindicates a displacement between the position of the pixel in which thecenter of the subject S is captured in a captured image and the positionof the pixel at the center of the captured image.

For example, when acquiring an image captured by the image capturingapparatus 31A (step S12 shown in FIG. 14), the information processingapparatus 10 corrects positional information such that the position ofeach pixel of the captured image is displaced by an amount indicated bya correction value corresponding to the image capturing apparatus 31A.

The same correction is performed on an image captured by the imagecapturing apparatus 31B and an image captured by the image capturingapparatus 31C. Thereafter, the information processing apparatus 10performs computation based on the corrected positional information instep S13 and the subsequent steps shown in FIG. 14.

Specifically, in contrast to a configuration with which positionalinformation is not corrected, the second modification of the informationprocessing apparatus 10 specifies, in a captured image that has beenselected or created, the pixel value of a pixel that is displaced by anamount indicated by the correction value corresponding to the imagecapturing apparatus 31 (step S19 shown in FIG. 14).

In this way, with the optical characteristics measuring method accordingto the embodiment of the present invention, when acquiring one or morecaptured images, the information processing apparatus 10 correctspositional information that indicates the positions of the pixels of oneor more images captured by each of the plurality of image capturingapparatuses 31.

With such a method, even if the position of the subject S is differentin each of the images captured by the plurality of image capturingapparatuses 31, it is possible to perform correction such that theposition of the subject S in each captured image is the same, and thengenerate a virtual image for each wavelength. Therefore, it is possibleto acquire even more preferable measurement results.

Also, in the optical characteristics measuring system 200 according tothe embodiment of the present invention, the information processingapparatus 10 can correct positional information indicating the positionof each pixel of one or more images captured by a plurality of imagecapturing apparatuses 31.

With such a configuration, even if the position of the subject S isdifferent in each of the images captured by the plurality of imagecapturing apparatuses 31, it is possible to perform correction such thatthe position of the subject S in each captured image is the same, andthen generate a virtual image for each wavelength. Therefore, it ispossible to acquire more preferable measurement results.

Other configurations and operations are the same as those of theabove-described optical characteristics measuring system 200, detaileddescriptions are not repeated here.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the scopeof the present invention being interpreted by the terms of the appendedclaims.

What is claimed is:
 1. An optical characteristics measuring method formeasuring optical characteristics of a subject, the opticalcharacteristics measuring method comprising: a step of acquiring one ormore captured images including the subject, using an image capturingapparatus that is located at a predetermined distance from the subject,and is configured to be displaceable relative to the subject, whilemaintaining the predetermined distance; and a step of creating, based onthe one or more captured images thus acquired, a virtual image includingthe subject and acquired from one or more analysis points each locatedat a position other than a position on a plane that includes thetrajectory of the image capturing apparatus.
 2. The opticalcharacteristics measuring method according to claim 1, wherein, in thestep of creating a virtual image, a plurality of virtual images acquiredfrom a plurality of analysis points are respectively created, and theoptical characteristics measuring method further comprises a step ofcalculating the sum of pixel values of each of the plurality of virtualimages thus created.
 3. The optical characteristics measuring methodaccording to claim 1, wherein, in the step of creating a virtual image,a captured image is selected from among a plurality of images capturedfrom the trajectory, based on a position on a virtual planecorresponding to the virtual image, the position of each of the one ormore analysis points, and the plane, and the virtual image is createdbased on the captured image thus selected.
 4. The opticalcharacteristics measuring method according to claim 3, wherein, in thestep of creating a virtual image, a plurality of captured images areselected from among a plurality of images captured from the trajectory,and the virtual image is created based on one image created from theplurality of captured images thus selected.
 5. The opticalcharacteristics measuring method according to claim 1, wherein, in thestep of acquiring one or more captured images, a plurality of imagecapturing apparatuses that respectively capture images with differentwavelengths are used, and in the step of creating a virtual image, thevirtual image is created for each of the plurality of image capturingapparatuses.
 6. The optical characteristics measuring method accordingto claim 5, wherein, in the step of acquiring one or more capturedimages, a plurality of image capturing apparatuses that are arrangedalong the circumference of the same circle that is centered around thesubject are used.
 7. The optical characteristics measuring methodaccording to claim 5, wherein, in the step of acquiring one or morecaptured images, positional information indicating the position of eachpixel of the one or more images captured by the plurality of imagecapturing apparatuses is corrected.
 8. The optical characteristicsmeasuring method according to claim 5, wherein, in the step of acquiringone or more captured images, a plurality of image capturing apparatusesthat respectively include light attenuation filters provided atpositions in an image capturing direction are used.
 9. An opticalcharacteristics measuring system that measures optical characteristicsof a subject, the optical characteristics measuring system comprising:an information processing apparatus; an image capturing apparatus thatis located at a predetermined distance from the subject; and a movablemechanism configured to be able to change the position of the imagecapturing apparatus relative to the subject while maintaining thepredetermined distance, wherein the information processing apparatus isconfigured to create a virtual image including the subject and acquiredfrom one or more analysis points each located at a position other than aposition on a plane that includes the trajectory of the image capturingapparatus, based on an image captured by the image capturing apparatusand including the subject.
 10. The optical characteristics measuringsystem according to claim 9, wherein the information processingapparatus is configured to create a plurality of virtual images acquiredfrom a plurality of analysis points respectively, and calculate the sumof pixel values of each of the plurality of virtual images thus created.11. The optical characteristics measuring system according to claim 9,wherein the information processing apparatus is configured to select acaptured image from among a plurality of images captured from thetrajectory, based on a position on a virtual plane corresponding to thevirtual image, the position of each of the one or more analysis points,and the plane, and create the virtual image based on the captured imagethus selected.